This invention relates to a transmission and reception system for controlling a locking/unlocking operation of a key, and more particularly to a transmission and reception system which uses a radio wave, an infrared ray or the like to control locking or unlocking of a door for a house, a vehicle or the like.
Conventionally, for the locking or unlocking of a door of a house, a vehicle or the like, it is generally known to deliver an instruction using a radio wave, an infrared ray or the like without using a physical key to effect locking or unlocking. FIG. 1 shows a typical known remotely controlled lock apparatus.
Referring to FIG. 1, the remotely controlled lock apparatus is denoted at 50 and includes an electronic lock 52 provided on a door 51, a transmitter 53 for transmitting a radio wave signal, a receiver 54 for receiving the radio wave signal, and a controller 55 for controlling locking or unlocking of the electronic lock 52 in response to the radio wave signal. The electronic lock 52, receiver 54 and controller 55 are connected to each other by a power line 56.
With the remotely controlled lock apparatus 50, if an owner depresses an operation button (not shown) of the transmitter 53 when the owner comes near the door 51, then a radio wave signal including an identification code ID of the owner and so forth is transmitted from the transmitter 53, and the radio wave signal is received by the receiver 54.
After the receiver 54 receives the radio wave signal, it transmits the identification code ID included in the radio wave signal to the controller 55. The controller 55 compares the identification code ID received from the receiver 54 with identification code ID set therein in advance. If the identification code ID of the radio wave signal and the identification code ID set in advance are coincident with each other, then the controller 55 sends a locking or unlocking signal to the electronic lock 52.
The electronic lock 52 is operated for locking or unlocking in response to the locking or unlocking signal so that the door 51 can be locked or unlocked automatically. Also an apparatus wherein a power supply and an electric lock are provided in a door so that locking or unlocking may be performed electrically is known and disclosed, for example, in Japanese Utility Model Registration No. 2,506,280 or Japanese Utility Model Laid-Open Application No. Heisei 1-129454.
However, the conventional remotely controlled lock apparatus 50 having such a construction as shown in FIG. 1 is disadvantageous in that a large space is required because the receiver 54, the controller 55 and so forth must be located, for example, in the inside of a house.
Further, in order to obtain power, for example, a power supply plug must be inserted into a plug socket to receive AC power supply from the outside of the receiver 54. Further, since the receiver 54, the controller 55 and so forth are not formed as a unitary member with the door 51, wiring lines between the door 51, receiver 54, controller 55 and so forth must be taken into consideration. Therefore, the remotely controlled lock apparatus 50 is disadvantageous also in that a large scale and much time are required to install it.
Furthermore, since the receiver 54 is installed in an exposed state, where a button for erasing or registering an identification code ID and so forth are provided on the receiver 54, the remotely controlled lock apparatus 50 is further disadvantageous in terms of safety in that an identification code ID may possibly be erased or registered readily.
On the other hand, as remotely controlled lock apparatus of the type described above become more popular, a still further disadvantage arises in that, when another user in the neighborhood to a user of a certain remotely controlled lock apparatus utilizes locking or unlocking by a radio wave of the same frequency to open or close a door of a house or a vehicle within a range within which the radio wave then reaches the certain remotely controlled lock apparatus, radio interference occurs, resulting in failure to open or close the door of the user of the certain remotely controlled lock apparatus, or the receiver 54 of the certain remotely controlled lock apparatus receives static electricity or an unnecessary signal and a malfunction of the receiver 54 is likely to occur.
Further, since the power supply to the receiver 54 is normally kept on or intermittently turned on, if the remotely controlled lock apparatus 50 is not used for a long period of time, then the power is consumed in vain within the time. The remotely controlled lock apparatus 50 is disadvantageous also in that, as the time within which the power supply is on increases, the frequency in which an unnecessary signal is received increases, resulting in an increase in the rate in which a malfunction occurs.